The National Weather Service will launch a new wireless alert to those in the path of destructive thunderstorms starting next month. Similar to special alerts for Tornado Warnings and Flash Flood Warnings, the National Weather Service will add a damage threat tag to some Severe Thunderstorm Warnings starting on August 2 to better convey the severity of the storm. The Wireless Emergency Alerts (WEA) system will broadcast the warning to cellphone users in the impact area.
To help communicate the severity of the storm, the National Weather Service is sorting storms by threat categories: base, considerable damage, and destructive damage.
“Base” and “considerable damage” storms still won’t trigger an alert. A “base” baseline severe thunderstorm still meets the standard definition for a severe storm: it has 1″ diameter hail (quarter-sized) and/or 58+ mph winds. A storm tagged with “considerable damage” has at least 1.75″ diameter (golf-ball sized) hail and 70+ mph winds.
However, a “destructive” storm will now trigger the special alert. The criteria for such a storm is that it has hail that is at least 2.75″ in diameter (baseball-sized) and/or has wind gusts over 80 mph. Storm warnings that meet this criteria will trigger a WEA alert on their smartphone.
According to the National Weather Service, the new destructive thunderstorm category “conveys to the public urgent action is needed, a life-threatening event is occurring and may cause substantial damage to property.” All National Weather Service Severe Thunderstorm Warnings will continue to be issued and distributed via weather.gov, NOAA Weather Radio, Emergency Alert System and through dissemination systems to emergency managers and partners, including the weatherboy.com website. The addition of damage threat tags are part of the broader Hazard Simplification Project to improve communication of watches and warnings to the public.
The National Weather Service says 13 of the 22 costliest weather disasters last year were severe thunderstorms. The new “destructive” tag would have activated a Wireless Emergency Alert for many of these impactful events, including the costliest thunderstorm in U.S. history, the $11 billion derecho that affected Iowa in August 2020.